my only suggestion is to really run him around before you need him to be still - oval, park, somewhere relatively safe.
For going out - have you tried a baby carrier on your back - sometimes the view from up there is different enough to distract (but it also means that he can reach all sorts of new things.....)

Could you put your playpen in the side of the front of the church - somewhere where the congregation isn't likely to go, and where Dad is visible??